4lb trilene fluoro works well for any situation trout fishing in the right length and no i don't nail knot a 9' piece to my fly line for nymphing or drys either one . make my own tappered then end up with 4lb trilene fluoro as tippet most of the time , steelies are 6lb seagar instead

Just my two cents...but mono works great for me on warm water situations and I just prefer actual tippet material for trout. The word supple came up earlier and I would have to second the importance of that quality. For steelhead, I love fishing six pound Seaguar Florocarbin. My tippet preference is Orvis Superstrong...that material has amazed me a couple times with its durability and it has saved some large fish for me.